Friction disc for disc brake

ABSTRACT

A friction disc such as a disc brake rotor having an annular core of material such as carbon or the like providing sliding frictional resistance and a heat sink for heat generated thereby. A retaining metal ring encircling the annular core is provided with circumferentially spaced-apart key slots adapted to engage drive keys suitably mounted to a wheel. A plurality of circumferentially spaced-apart radially extending openings in the retaining ring are adapted to receive associated drive pins or rods which extend therefrom through radially extending passages in the annular carbon core. Braking torque loads generated by the annular carbon core which bears against the drive pins are transmitted by the latter to the retaining ring which, in turn, bears against the drive keys.

United States Patent 1 Stout [111 3,747,712 1 July 24, 1 973 154]FRICTION DISC FOR DISC BRAKE [75 Inventor: Gilbert T. Stout, South Bend,Ind. [73] Assignee: The Bendix Corporation 3 22 Filed: Sept. '20, 1971[21] Appl. No.: 181,778

[52] US. Cl. 188/73.2, 188/218 XL, 192/107 R [51] Int. Cl. F1611 65/12[58] Field of Search 188/218 A, 218 XL, 188/251 A, 23.2; 192/107 M, 107R [56] References Cited UNITED STATES PATENTS 3,507,370 4/1970 Falch188/218 XL 2,485,082 10/1949 Bachman... 188/218 XL 3,473,637 10/1969Rutt 192/107 R FOREIGN PATENTS OR APPLICATIONS 1,151,276 7/1963 Germany188/218 XL 848,029 9/1960 Great Britain 188/218 A PrimaryExaminer-George E. A. l-Ialvosa Attorney-Gordon l-I. Chenez et al.

[57] ABSTRACT A friction disc such as a disc brake rotor having anannular core of material such as carbon or the like providing slidingfrictional resistance and a heat sink for heat generated thereby. Aretaining metal ring encircling the annular core is provided withcircumferentially spaced-apart key slots adapted to engage drive keyssuitably mounted to a wheel. A plurality of circumferentiallyspaced-apart radially extending openings in the retaining ring areadapted to receive associated drive pins or rods which extend therefromthrough radially extending passages in the annular carbon core. Brakingtorque loads generated by the annular carbon core which bears againstthe drive pins are transmitted by the latter to the retaining ringwhich, in turn, bears against the drive keys.

5 Claims, 5 Drawing Figures Pmemw 3.747.112

SHEET 1 OF 2 FIG.

INVENTOR. GILBERT T. STOUT AGENT Pmamammz 3.747. 712

SHEEI 2 0F 2 INVENTOR. GILBERT T. STOUT AGE/VT FRICTION DISC FOR DISCBRAKE BACKGROUND OF THE INVENTION In disc brakes and multiple disc highcapacity aircraft brakes, in particular, various materials such ascarbon, berrylium, etc., have been substituted for conventional steelrotors and/or stators in an attempt to improve the brake efficiency andlife under adverse conditions such as extreme heat and temperatureexperienced in braking large heavy aircraft as, for example, jetaircraft which land at relatively high speed. The substitution ofcarbon, berrylium, etc. for steel has shown a marked improvement in theability of the brake rotors and/or stators to function efficiently withreduced maintenance problems and relatively longer life under the mostadverse braking requirements. However, a significant disadvantage ofsuch materials, for example, carbon, is the characteristically lowstrength thereof in tension and/or shear modes which requires carefulconsideration of the manner in which brake torque loads are imposedthereon if structural failure is to be avoided. A carbon rotor or statorhas satisfactory strength in a compression mode thereby enabling it towithstand the brake loads providing the load is not localized. Variousrotor and/or stator disc structures have been proposed wherein a carboncore, either one piece or segmented, is carried by a metal frame orretaining member which, in turn, is suitably keyed to a wheel in thecase of a rotor or to a fixed torque absorbing member in the case of astator. Reference is made to U.S. Pat. No. 3,403,759 issued Oct. 1, 1968in the name of O. L. Holcomb, Jr., U.S. Pat. No. 3,483,953 issued Dec.16, 1969 in the name of John R. Bender and U.S. Pat. No. 3,548,979issued Dec. 22, 1970 in the name of John P. Nelson et al for examples ofsuch prior art. However, such prior art rotor and/or stator structuresare not entirely satisfactory from the standpoint of structuralcomplexity and associated fabrication costs, maintenance problems andweight among other disadvantages as will be recognized by those personsskilled in the art.

In summary, the present invention provides a rotor disc wherein anannular carbon friction disc is subjected to compressive force as aresult of bearing against a plurality of circumferentially spaced-apartrods or pins extending radially therethrough which rods or pins aresecured to a metal retaining ring encircling the carbon disc andprovided with circumferentially spaced-apart recesses adapted to matewith associated drive keys fixedly secured to a wheel.

It is an object of the present invention to provide a simple andstructurally strong friction disc including an annular carbon member.

Referring to FIG. 1, there is shown an aircraft wheel and brake assemblyof the multiple disc type. The wheel may be formed of two half portionsonly one of which designated by 12 is shown. A plurality of bolts 14,only one of which is visible, fixedly secure the two half portionstogether. The wheel 10 is rotatably mounted on a fixed stub-axle 16forming part of the aircraft landing gear, not shown, by conventionalbearing means 18. A non-rotatable annular carrier member 20 secured toaxle 16 by conventional fastening means, not shown, is provided with aplurality of fluid pressure actuated motors 22 each of which includes achamber 24 adapted to receive a sleeve 26 threadedly engaged withcarrier member 20. A piston 28 slidably carried in sleeve 26 is providedwith a block'of heat insulation material 30 fixedly secured thereto bysuitable fastening means such as a bolt 32. The piston 28 is actuated bypressurized fluid supplied to chamber 24 via a conventional fluiddistributing system, now shown, including brake fluid pressure controlmeans controlled by the aircraft pilot.

A torque tube 34 including an annular backing plate 36 is fixedlysecured to carrier member 20 by a plurality of spaced-apart bolts 38only one of which is shown.

A plurality of axially spaced-apart annular rotor discs 40 are suitablysplined for axial movement along a .mating key member 42 fixedly securedto wheel 10. A plurality of annular stator discs 44 interleaved withrotor discs 40 are suitably splined for axial movement along a matingkey member 46 fixedly secured to torque tube The rotor discs 40 andstator discs 44 are frictionally engaged when compressed togetherbetween backing plate 36 and an annular pressure plate 48. The pressureplate 48 suitably splined to torque tube 34 for axial movement thereonis actuated by motors 22 engageable therewith. It will be recognizedthat frictional engagement of the rotor and stator discs 40 and 44results in a corresponding brake torque resistance to rotation of wheel10 which brake torque is absorbed by non rotatable torque tube 34.

Referring to FIGS. 2 and 3, a rotor disc 40 includes an annular carboncore 50 which is encircled by a metal ring 52 having circumferentiallyspaced-apart key engaging slots or recesses 54 formed therein.Intermediate slots 54 the ring 52 is provided with a reduced width bossportion 56 and a radially extending opening 58 formed in the bossportion 56. The opening 58 is aligned with an opening or bore 60 formedin carbon core 50 and extending radially therethrough. A metal rod orpin 62 slidably received by opening 58 extends radially inwardlytherefrom into opening 60 with a relatively loose fit with the latter.Diametrically opposed openings 64 in boss portion 56 are aligned with adiametrical passage 66 in pin 62 to permit insertion of a fasteningmember such as cotter pin 68 to retain pin 62 in position. It will benoted that sufficient clearance is provided by the reduced width of bossportion 56 to accommodate the head and tang portions of cotter pin 68which do not extend beyond the associated opposite friction surfaces ofcore 50.

Referring to FIGS. 4 and 5, the rotor disc 40 is shown with a segmentedcarbon core in which case a plurality of carbon segments 70 are arrangedto form a substantially continuous annular carbon core. Each bossportion 56 is lengthened circumferentially to accommodate two openings58 having a spaced-apart relationship. A carbon segment 70 is providedwith two spacedapart radially extending openings 60 which receiveassociated rods or pins 62 extending from openings 58.

As in the case of H6. 2, cotter pins 68 serve to secure pins 62 inposition on ring 52. i

It will be assumed that the pistons 28 are energized by pressurizedfluid in chamber 24 to compress the rotor and stator discs 40 and 44together between pressure plate 48 and backing plate 36 thereby creatingfrictional resistance and thus braking torque tending to resist rotationof rotor discs 40 and thus wheel 10 con-' nected thereto by virtue ofthe force transmitting metal pins 62 and ring 52. To that end, thecarbon core 50 is caused to bear against pins 62 each of which engagesthe adjacent wall of associated opening 60 with the highest bearingforce load distributed longitudinally thereagainst at the mid section ofcore 50 or in other words, along the line of contact between pin 62 andadjacent wall. The resulting tangentially directed bearing load againstcarbon core 50 produces a corresponding compressive stress in core 50which as pointed out heretofore is the most favorable strengthcharacteristic of the carbon material.

It will be recognized that the carbon material is compressible to alimited extent thereby permitting the effective bearing area between pin62 and adjacent wall of opening 60 to increase as the bearing loadtherebetween increases until maximum bearing area is established.Preferably, the clearance between pin 62 and wall of opening 60 is heldto a minimum to avoid an interference fit between pin 62 and opening 60and yet compensate for differential thermal expansion between pin 62 andcarbon core 50.

As the effective bearing area increases in the abovementioned manner theforce per unit area imposed on the wall of opening 60 progressivelydecreases from the mid section of core 50 to the opposite frictionsurfaces thereof thereby establishing a corresponding reduction instress in the region of the friction surfaces of core 50.

Referring to FIGS. 4 and 5, the braking torque derived from the segments70 is transmitted via pins 62 and ring 52 to wheel in the same manner asdescribed above with regard to FIGS. 2 and 3. However, the use of twopins 62 in each segment 70, which pins 62 extend radially through thesegment 70, tends to restrain segment 70 against radially inwardlymovement relative to ring 52 as well as reduce the effective bearingload imposed against segment 70 in comparison to that experienced by asingle pin 62 arrangement.

It will be understood that the present invention is not restricted touse in connection with a rotor disc but, as will be recognized by thosepersons skilled in the art, is adaptable to use in a stator disc.

I claim:

1. A friction disc for a multiple disc brake for retarding rotation of awheel member mounted on a fixed axle member, said friction disccomprising:

an annular friction member defined by a plurality of arcuate segmentsarranged end to end formed of relatively brittle friction materialcharacterized by strength weakest in tension and shear modes;

a retaining ring concentric with said annular member and abutting one ofthe circumferential edges thereof;

a plurality of circumferentially spaced-apart radially extendingopenings in said retaining ring;

a plurality of circumferentially spaced-apart radially extending boresor openings in said annular member at least two bores being provided ineach segment;

a pin retained at one end by each of said plurlaity of openings andextending therefrom into an associated one of said bores; and key meansoperatively connecting said retain-ing ring to one of said wheel andaxle members and permitting axial movement of said retaining ringrelative to said wheel and axle members.

2. A friction disc as claimed in claim 1 wherein:

said pins are removably secured to said ring by fastening meansextending transversely therethrough.

3. A friction disc as claimed in claim wherein:

said retaining ring is engageable with the radially outward edge of saidannular member; and

said key means includes a plurality of circumferentially spaced-apartaxially extending key members operatively connected to said wheel memberand said retaining ring.

4. A friction disc as claimed in claim 1 wherein:

said pins are slidably received by said bores with a non-interferencefit therebetween'.

5. A friction disc as claimed in Claim 1 wherein said key means includescircumferentially spaced-apart axially extending key members operativelyconnected to said retaining ring intermediate said openings therein.

1. A friction disc for a multiple disc brake for retarding rotation of awheel member mounted on a fixed axle member, said friction disccomprising: an annular friction member defined by a plurality of arcuatesegments arranged end to end formed of relatively brittle frictionmaterial characterized by strength weakest in tension and shear modes; aretaining ring concentric with said annular member and abutting one ofthe circumferential edges thereof; a plurality of circumferentiallyspaced-apart radially extending openings in said retaining ring; aplurality of circumferentially spaced-apart radially extending bores oropenings in said annular member at least two bores being provided ineach segment; a pin retained at one end by each of said plurlaity ofopenings and extending therefrom into an associated one of said bores;and key means operatively connecting said retain-ing ring to one of saidwheel and axle members and permitting axial movement of said retainingring relative to said wheel and axle members.
 2. A friction disc asclaimed in claim 1 wherein: said pins are removably secured to said ringby fastening means extending transversely therethrough.
 3. A frictiondisc as claimed in claim wherein: said retaining ring is engageable withthe radially outward edge of said annular member; and said key meansincludes a plurality of circumferentially spaced-apart axially extendingkey members operatively connected to said wheel member and saidretaining ring.
 4. A friction disc as claimed in claim 1 wherein: saidpins are slidably received by said bores with a non-interference fittherebetween.
 5. A friction disc as claimed in Claim 1 wherein: said Keymeans includes circumferentially spaced-apart axially extending keymembers operatively connected to said retaining ring intermediate saidopenings therein.